Ancient Greeks and Romans used metallic lead blocks to draw lines on wax tablets and parchment, leaving faint gray marks. People mistook graphite for the same substance as lead, hence the term "lead pencil" has been handed down to this day. In fact, modern pencils contain no metallic lead at all.

The core of a pencil is mainly composed of graphite and clay. Graphite is a scaly solid with metallic luster, featuring carbon-carbon chemical bonds within each layer, while van der Waals forces exist between adjacent layers. Carbon-carbon bonds are highly stable and extremely difficult to break. This explains why diamond and graphite, both pure carbon substances, differ drastically in physical properties and market value. The human body contains no substances capable of breaking carbon-carbon b

Pencils are categorized into three forms: natural wooden barrel pencils, pre-sharpened pencils, and capped pencils.

As early as Ancient Greece and Ancient Rome, people polished pure metallic lead into thin sticks to draw marks on wax tablets and stone slabs, leaving pale gray traces.

Composed of half graphite and half clay with moderate hardness. It delivers medium gray lines with crisp strokes and is not prone to smudging.

Colored pencils with smooth surface, centered and intact leads, or retractable leads with end protection are less likely to break.